Xiaoming and Xiaogang collect some glass balls. The number of glass balls of Xiaoming is three times that of Xiaogang. If Xiaoming gives Xiaogang 6 Xiao Ming and Xiao Gang collected some glass balls. Xiao Ming's number of glass balls is three times that of Xiao Gang. If Xiao Ming gives Xiao Gang six, they will have the same number. How many glass balls do they have?

Let Xiaogang have X
3X-6=X+6
3X-X=6+6
2X=12
X=6
Xiaoming = 6 * 3 = 18

English translation
I have to stay at home on school nights. Why is it good to volunteer!

First, to make learning history a real experience
I have to stay at home on school nights
Third, why is it good to volunteer?
Fourth: the other day

When the gardener uses the scissors as shown in the figure to trim the branches, he often puts the branches as close as possible to the scissors axis O. The purpose of doing this is to ()
A. Reduce the resistance B. increase the power arm to save more effort C. reduce the resistance arm to save more effort D. save more distance

In the same case, approach to the scissors axis O to reduce the resistance arm, while the resistance and power arm remain unchanged. It can be seen from f1l1 = f2l2 that it will save labor; therefore, select C

The sum of the edges of a cuboid is 96 cm. It is known that the length is 10 cm, the height is 8 cm and the width is 10 cm______ Cm

96 △ 4 - (10 + 8) = 24-18 = 6 (CM) answer: the width is 6 cm

A math problem in sixth grade
Among the five numbers in the following questions, choose the number that is different from the other four numbers, cross it out, and then choose a suitable number from the brackets
1.42,20,18,48,24
（21,54,45,10）
2.15,75,60,45,27
（50,70,30,9）
3.42,126,168,63,882
（27,210,33,25）

1.
Cross out 20 and add 54
Both contain a factor of 6
two
Cross out 27 and add 30
Both contain a factor of 15
three
Cross out 63 and add 210
Both contain a factor of 42

The concept of positive and negative numbers

1. A number larger than 0 is called a positive number. There is a sign "+" in front of a positive number, which can be omitted. There are countless positive numbers, including positive integers, positive fractions and positive irrational numbers. Geometric meaning of positive numbers: the points representing positive numbers on the number axis are on the right side of 0. 2. Negative numbers are mathematical expressions, which refer to real numbers less than 0, A negative number is the opposite of a positive number with absolute value. Any positive number preceded by a negative sign is a negative number. On the number axis, negative numbers are on the left side of 0, and all negative numbers are smaller than natural numbers. Negative numbers are marked with a minus sign

Mathematics falls into several categories

The content of mathematics is very extensive, it has many branches. So far, there is no recognized principle of division. But as far as the connection between mathematics and real life is concerned, it can be roughly divided into two categories, namely pure mathematics and applied mathematics
1. Pure mathematics
Pure mathematics studies the internal relations of mathematical laws abstracted from the objective world, and it can also be said to study the laws of mathematics itself
This paper studies the geometry class of space form, the algebra class of discrete system and the analysis class of continuous phenomenon
Differential geometry is the study of smooth curves and surfaces. It uses mathematical analysis and differential geometry as research tools. It has a wide range of applications in mechanics and some engineering problems (such as elastic shell structure, gears and so on). Topology is the study of the invariability of geometric figures under one-to-one continuous transformation, This property is called "topological property". For example, when the rubber film is deformed but not broken or folded, the closure of the curve and the intersection of the two curves remain unchanged
It belongs to the second category, such as number theory and modern algebra. Number theory is a subject that studies the properties of integers. According to different research methods, it can be roughly divided into elementary number theory, algebraic number theory, geometric number theory, analytic number theory, etc, It discusses the properties and structures of groups, rings, vector spaces and so on. Modern algebra includes group theory, ring theory, Galois theory and other branches. It has a wide range of applications in analytical mathematics, geometry, physics and other disciplines
It belongs to the third category, such as differential equation, function theory and universal implication analysis. Differential equation is an equation containing the derivative or partial derivative of unknown function. If the unknown function is a function of one variable, it is called ordinary differential equation. If the unknown function is a function of many variables, it is called ordinary differential equation, Function theory is the general term of real function theory (the study of real valued functions in the range of real numbers) and complex variable function (the study of the properties of functions in the plane of complex numbers). Universal implication analysis is the comprehensive use of function theory, geometry and algebra to study the functions, operators and limit theory in infinite dimensional vector space (such as function space), It is a set of functions with some common properties. It is widely used in mathematics and physics

Which are prime numbers in 12,13,15,21,23,25,31,32,35,51,52,53

13、23、31、51、53

Is buoyancy related to depth

It doesn't matter. According to Archimedes' theorem, the buoyancy of the object invading the liquid is equal to the gravity of the liquid. It can be concluded that the buoyancy is related to the density of the liquid and the volume of the liquid

Translation of part 3a of English book in the second semester of 2011 junior high school (all)

I hope I can open a crystal ball collector's club. By the way, what are your hobbies? I love you, Ellen

English translation I have to stay at home on school nights. Why is it good to volunteer!